In commercial refrigeration systems such as are employed in supermarkets, the refrigeration system includes a bank or rack of compressors, a condenser and a plurality of evaporators in the various display cases. Ice cream is peculiar in that it must be kept colder than most other frozen foods or else the package will be "soft" to the touch and less salable. Of course, deep freezing is best for and does not hurt the product but maintaining an excess temperature reduction comes at a price. To achieve the 0.degree. F. proper storage temperature for ice cream, a typical saturated suction temperature would be -35.degree. F. whereas -25.degree. F. would be satisfactory for other frozen foods. Thus, an individual compressor on the rack, called the satellite compressor, is normally used to refrigerate the ice cream. Specifically, all of the compressors in the rack use the same condenser, but the satellite compressor only receives suction vapor from the evaporator(s) in the ice cream display case(s). Upon failure of the satellite compressor, refrigeration is lost in the ice cream display case(s).
An alternative to the use of a satellite compressor is to place a pressure regulator at the outlet of each of the display cases except the ice cream case(s). All of the compressors would operate at -35.degree. F. saturated suction temperature. This alternative is inefficient and complex.